/*Khi link duoc di chuyen chuot*/
a:hover{
    color: red;
    text-decoration: none;
}
/*Khi link chua duoc tac dong*/
a{
    text-decoration: none;
}
/*Khi link dang duoc click chuot*/
a:active{
    color: red;
}
/*Trang thai nguoi dung da click vao truoc do*/
a:visited
{
    color: black;
}

.panel
{
    margin: 20px;
}